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Turn Up The Power


pashley-phil
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hey all,

Right i've got a vw transporter it an old one, r reg, and when i go up hill in 5th or 4th and the revs are low it really struggles, but if the revs are like 3700rpm it pulls quite well, i'm guessing that is because the turbo has cut in, so am i right in thinking that if i turned the turbo up that it will kick in quicker therefore giving me better power on lower revs??

second question does anyone know how to turn the turbo up :D

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You need anti lag. It's where the valve timing is retarded so the combustion takes place partly in the exhaust manifold due to fuel dumping. That spools up the turbo and will reduce lag.

It's common practice with diesel engines.

sweet sounds like you know your stuff :D

How do i go about anti-lag is it as easy as buying something and sticking it some where?

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I don't want to be "that guy" so I'll say it straight away - I was taking the piss a bit. Anti lag is used in rally cars and damages the engine, exhaust and turbo. Doing it to a diesel might not even be possible, I don't know.

You can chip tune a diesel engine but it is normal for the older ones to have turbo lag. If you want to get rid of it, you'll be better off with changing the car to one with a more modern engine. Otherwise there's not much you can do other than change your driving style.

Edited by Greetings
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Yep I agree with Matt in my experience with all the turbo Diesel's the power band is a low rev so on acceleration change up a gear at the peak power and then lead into the nexts gears. Theres no way I would be going up any slope in a diesel in 4th or 5th gear! You really just gotta rag every gear for all its worth, (by that its totally different to a petrol, revving the nuts off it won't get you anywhere!)

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i found with my audi tdi, blocking off the egr valve seemed to help the engine a little bit, less smoke and seemingly more torque (definately better mpg!)

You could try a free-er flowing exhaust, but again the difference will be minimal!

Blocking off the egr will always improve power and fuel economy, all it does is recycle the exhaust gasses back into the inlet manifold, thus reducing the amount of fresh, clean air available for engine charge. Its common practise on modern motorbikes to block/remove it immediately as part of the uncorking process :)

Probably plays havoc with your emmissions though!

I may be being daft but Im sure you can wind the turbo up on vw transporters, Jody@midlandvw does on his if he needs it to go quick :D There may be other settings to change though, I dunno, know bugger all about turbos :$

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Wouldn't a smaller turbo spool up quicker? It'd also produce less power. It's a bit of an extreme modification when dropping down a gear will do the trick, lol.

I dont think its the spool time of the turbo thats causing an issue, more the rev range at which it comes onto boost, all a smaller turbo would theoretically do is reduce the spool time and peak power. You would think that vw would set the turbo to spool up when the engine is making maximum torque, from what Ive experienced from driving diesel vans in that the turbo starts spooling almost from idle, 3700rpm sounds higher than I would have expected :unsure:

edit: Im not even sure if this is a diesel or petrol van, 3700 rpm probably sounds about right for a petrol engine spool up rev range.

Edited by forteh
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The turbo is spun by the exhaust gasses, meaning in theory the only way to make it start producing positive boost any earlier is to either reduce the exhaust turbine size, meaning it'll spin faster from the same gas flow, but then it'll spin with less force, meaning lower peak boost. Or to increase the amount of exhaust gas flow, ie increase the volumetric efficiency of the engine when running off boost. So I guess that'd be porting, decent manifolds, ect, breathing mods basically.

By upping the boost with the standard turbo all you'll be doing is increasing the threshold at which the engine decides the turbo's spinning too fast, the point being, for it to make any difference, the turbo already has to be spinning a fair bit and making a decent amount of boost in the first place, so no, it wont give you any additional low end grunt at all.

I'm guessing now that it'll be a 1.9tdi, as my dad's got a 2.5tdi transporter, and it doesn't particular issue with hills, so you may find that if you're serious about this, something like an inlet manifold off a PD130 engine will increase the airflow slightly before it comes on boost, helping it boost earlier, but I shouldn't have thought it'll be an easy bolt on mod, and neither will much else that'll help dramatically. Unless there's some sort of blindingly obvious breathing restriction on these engines that's easily removed.

The best bet I'd have thought, will be as said, to just change down a gear, although blanking off the EGR valve wouldn't hurt, and you could look into fiddling with the pump to get a bit more power when off boost, but I wouldn't know where to start with this. The extent of my knowledge of VW diesel pumps is pretty much: I think they might be made by bosch, and they don't have any particular issue with vegetable oil.

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The turbo is spun by the exhaust gasses, meaning in theory the only way to make it start producing positive boost any earlier is to either reduce the exhaust turbine size, meaning it'll spin faster from the same gas flow, but then it'll spin with less force, meaning lower peak boost. Or to increase the amount of exhaust gas flow, ie increase the volumetric efficiency of the engine when running off boost. So I guess that'd be porting, decent manifolds, ect, breathing mods basically.

By upping the boost with the standard turbo all you'll be doing is increasing the threshold at which the engine decides the turbo's spinning too fast, the point being, for it to make any difference, the turbo already has to be spinning a fair bit and making a decent amount of boost in the first place, so no, it wont give you any additional low end grunt at all.

Turbo lesson over, thank you, see I know bugger all about turbos :D

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Some of those old transporters have not very much power (like 60 bhp) so I'm not surprised it can't go up hills in 5th. All this talk about turbos is missing the point a bit - You just need to change gear, and accept that you're driving an underpowered van up a hill, and it's not going to be that fast.

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What's the readline set at on your van? The other issue could be that it's making less torque than it should at lower revs which could point to an issue elsewhere. Simply turning up the boost pressure will not solve this problem as you want to shift the power band down the rev range. To get the turbo to spool faster, you need to increase the volume and speed of gas going through it at lower revs to overcome the inertia of the turbo wheel. This would drive you down the route of changing manifolds (exhaust and inlet), changes to the engine's timing and mapping etc etc, simply put it isn't a simple job.

You could put a smaller turbo on, that would spool faster and move peak power down the rev range, but it will impact on peak power so you may find it accelerates better in low rpms, but has a loss of power higher up which I personally think would mean you'll struggle even more going up hills.

The simplest thing to do is manage your gear changes to keep the revs at peak power and therefore maximising the power you have in the engine as it is.

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cheers guys

i also asked on the vwt4forum and they come back with this which seems good

There are a few mods that you can do to increase power, and they can pretty much be done for not much ££££££

Buy a boost gauge, increase the boost buy adjusting the actuator rod, then increase the fuel by adjusting the fuel screw on the pump.

Next step either fit a decat (£40 ish) and then cobble up an intercooler, this will allow you to run a bit more boost safely

Last thing that could be done would be to fit an AAZ pump, this increases fuel inline with boost giving better acceleration. But you'll prob find the increase in boost and fel screw will be enough

There are loads of guides on here how to do it all, check out the technical articles aswell

I might try this tomorrow as i've got the day off :D

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cheers guys

i also asked on the vwt4forum and they come back with this which seems good

There are a few mods that you can do to increase power, and they can pretty much be done for not much ££££££

Buy a boost gauge, increase the boost buy adjusting the actuator rod, then increase the fuel by adjusting the fuel screw on the pump.

Next step either fit a decat (£40 ish) and then cobble up an intercooler, this will allow you to run a bit more boost safely

Last thing that could be done would be to fit an AAZ pump, this increases fuel inline with boost giving better acceleration. But you'll prob find the increase in boost and fel screw will be enough

There are loads of guides on here how to do it all, check out the technical articles aswell

I might try this tomorrow as i've got the day off :D

yea but none of the,m are actually addressing the issue youve got, which is lack of power at lower revs. all the things above will increase power, but only at the top end of the rev range, where youve already explained your van is fine at.

The decat will allow a free-er flow of gases through the exhaust system, but at lower revs that isnt gunna do anything worth talking about, and is £40.

ive never heard of an AAZ pump, but then im an idiot. but crucially, unless youve got a problem with there being not enough fuel being available to the pump, an extra/more poweful inline pump wont help, and if it was an issue with not enough fuel being available to the pump, then youd see worse performance at higher revs, which your not, your issues are all low down.

adjusting the wastegate actuator has already been discussed, and wont do jack till the turbo stops boosting at whatever revs the power drops off in your van at(dont know, 4100-4200 rpm maybe), at that point, youll get more power for an extra couple of hundred rpm.

your intercooler idea, is again, a bit of a waste, since the idea of an intercooler is to cool the compressed air from the inlet side of the turbo(since pressure causes an increase in heat, the charged air will be warmer than the air outside) but again until you get to the top end of the rev range, i doubt youll notice a difference. (since till you reach the speed the turbo spools at, there will be no extra heat, and at lower revs, where the turbo has kicked in, your not going to be getting much of a pressure(heat) increase. then by the time youve took away the drawbacks of the elongated passage the air has to travel to pass through the intercooler, your back at square one (and if the intercooler is placed atop the engine, like on the 2.5 tdi's, you may actually be increasing the temperature of the air, by having the heat exchange taking place right above a hot engine.

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yea but none of the,m are actually addressing the issue youve got, which is lack of power at lower revs. all the things above will increase power, but only at the top end of the rev range, where youve already explained your van is fine at.

The decat will allow a free-er flow of gases through the exhaust system, but at lower revs that isnt gunna do anything worth talking about, and is £40.

ive never heard of an AAZ pump, but then im an idiot. but crucially, unless youve got a problem with there being not enough fuel being available to the pump, an extra/more poweful inline pump wont help, and if it was an issue with not enough fuel being available to the pump, then youd see worse performance at higher revs, which your not, your issues are all low down.

adjusting the wastegate actuator has already been discussed, and wont do jack till the turbo stops boosting at whatever revs the power drops off in your van at(dont know, 4100-4200 rpm maybe), at that point, youll get more power for an extra couple of hundred rpm.

your intercooler idea, is again, a bit of a waste, since the idea of an intercooler is to cool the compressed air from the inlet side of the turbo(since pressure causes an increase in heat, the charged air will be warmer than the air outside) but again until you get to the top end of the rev range, i doubt youll notice a difference. (since till you reach the speed the turbo spools at, there will be no extra heat, and at lower revs, where the turbo has kicked in, your not going to be getting much of a pressure(heat) increase. then by the time youve took away the drawbacks of the elongated passage the air has to travel to pass through the intercooler, your back at square one (and if the intercooler is placed atop the engine, like on the 2.5 tdi's, you may actually be increasing the temperature of the air, by having the heat exchange taking place right above a hot engine.

This pretty much covers what I was going to say, and I agree that almost everything you listed, while it will give you more top end power, it won't give you anything lower down where you claim you have the problem.

The exception is the decat. By removing pressure from the exit of the turbo you get two benefits due to the increased mass flow through the turbine. Firstly is an increase in peak power as already mentioned, but secondly you will be able to spool the turbo slightly quicker as the back pressure in the exhaust limits the gas's ability to spool the turbo. The increase in spool then depends on how your wastegate is controlled. If mechanically then the increased spool will be more noticable, if electronically, then the effect of the decat could be masked by the way the wastegate is controlled by the ecu (this is seen when I decatted my rx7, the electronic boost control prevented the turbo from spooling until the set rpm in the ecu). So you may or may not get a benefit.

Knock-on effects of the decat include increased noise, increased emissions (possible MOT failure) and you could run into fueling issues if your ecu can't deal with the extra airflow to the engine (granted the increase won't be great, but it all depends on what margin the ecu's fuel tables have, some allow a healthy increase in boost, others like my rx7's don't).

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This pretty much covers what I was going to say, and I agree that almost everything you listed, while it will give you more top end power, it won't give you anything lower down where you claim you have the problem.

The exception is the decat. By removing pressure from the exit of the turbo you get two benefits due to the increased mass flow through the turbine. Firstly is an increase in peak power as already mentioned, but secondly you will be able to spool the turbo slightly quicker as the back pressure in the exhaust limits the gas's ability to spool the turbo. The increase in spool then depends on how your wastegate is controlled. If mechanically then the increased spool will be more noticable, if electronically, then the effect of the decat could be masked by the way the wastegate is controlled by the ecu (this is seen when I decatted my rx7, the electronic boost control prevented the turbo from spooling until the set rpm in the ecu). So you may or may not get a benefit.

Knock-on effects of the decat include increased noise, increased emissions (possible MOT failure) and you could run into fueling issues if your ecu can't deal with the extra airflow to the engine (granted the increase won't be great, but it all depends on what margin the ecu's fuel tables have, some allow a healthy increase in boost, others like my rx7's don't).

Cheers for taking your time to write this, it very helpful, i dont believe my van has an ecu? only because my naughbour said to me that it couldn't be chipped. maybe i'll see what other people has done, or i might just buy a 2.5 one, it'll be cheaper in the long run :D

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Cheers for taking your time to write this, it very helpful, i dont believe my van has an ecu? only because my naughbour said to me that it couldn't be chipped. maybe i'll see what other people has done, or i might just buy a 2.5 one, it'll be cheaper in the long run :D

I imagine it will have one, it would have to be pretty old not to. Whether it can be chipped is another matter really.

How old is the van?

Again looking at what others have done is all very well, but be clear about what it is you want to change, do you want more power at the top end (which is what the vast majority of "quick" modifications will acheive) or do you want to increase power low down (which is more complicated and costly to acheive properly).

I think you should probably go for the 2.5, the extra displacement will give you an increase in torque throughout the rpm range and will produce more low down power (as well as more at the top too).

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drop it a cog and rev the ball out of it! only way to drive an old diesel. in my experience!!

Yep I agree with Matt in my experience with all the turbo Diesel's the power band is a low rev so on acceleration change up a gear at the peak power and then lead into the nexts gears. Theres no way I would be going up any slope in a diesel in 4th or 5th gear! You really just gotta rag every gear for all its worth, (by that its totally different to a petrol, revving the nuts off it won't get you anywhere!)

Both bollox my K reg L200 laughed at hills in 5th

Change back to smalled rims.

The ones you put on it look f**king pimp, but they are too big man. :(

Are these wheels considerably bigger as in the total diameter bigger than before?

If so Jack may have a point here.

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the van is an r reg is a 1.9tdi

the wheels are a little wider i think they are 235 rather then 195 or something like that but the diameter is the same as the profile has gone down. so my old wheels where 15'' with massive side walls but the allys are 18'' with low profiles when i stood them next to each other they where the same height :D

philsvan.jpg

newvan008.jpg

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